  {  Tatjana Petrova
     2012 / 09 / 23
     This program finds  double square of triangle.}


program DoubleSquareOfTriangle;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  x1,y1,x2,y2,x3,y3, S : integer;
  fin : textfile;

begin
  assignFile(fin, 'input.txt');
  reset(fin);
  read(fin, x1,y1,x2,y2,x3,y3);
  closeFile(fin);
  S := abs(-x1*y2+x2*y1-x2*y3+y2*x3-x3*y1+x1*y3);
  writeln(S);
  readln;
end.
